1. Field of the Invention
The invention relates to internal magnetic shielding means for a cathode ray tube, and more particularly to improved CRT shielding means for tubes utilized in color display applications, such means being facilely fabricated and evidencing strengthening features, lightness in weight, and minimum of bulk.
2. Description of the Prior Art
Cathode ray tubes, such as those used in color television and related display applications, are often individually provided with a magnetic shielding arrangement to protect them from numerous stray voltages, currents, and magnetic fields, including the earth's magnetic field, which tend to adversely effect the desired performance of the tube. While shielding means oriented to externally encompass the funnel portion of the tube have been extensively utilized, it has been found that magnetic shielding means internally disposed within the tube envelope provide better shielding, thereby promoting marked improvement in tube performance.
In one phase of the prior art, substantially infundibular (funnel)-shaped internal shields have been positioned rearward of the screen masking member and affixed to the frame thereof. These shields are relatively expensive to fabricate and install, and represent the addition of considerable bulk and weight to the host mask-frame assembly.
A lighter and less bulky type of internal shielding means is also evidenced in the art as a pair of elongated open metallic channel-like members each having planar sides and a flat bottom intermediate thereto. These members are affixed to the top and bottom portions of the mask framing member in facing relationship. The terminal portions of these channel members are cut, bent, and welded to provide closed ends for the structure. The manufacture of these box-like closed-ended members represents several fabrication steps which are reflected in the final cost of such structures.